That attitude is part of what's so wrong with the world today. It doesn't just apply to animals, it applies to everything. Can you worry about every little thing? No, of course not. You'd go crazy trying. But when something directly affects you, such as you killing a kitten, albeit unintentionally, with your car, I think it's pretty cold for you to not be bothered by it. That fact that you weren't chills me, in fact. I was coming home from work one night and came upon a kitten writhing in the road. Some one had hit it and kept going. It was screaming, and that image bothers me even years later. I called a non-emergency number as soon as I got home and asked that they send someone out to end its suffering. 🙁